In transmission structures for street cars, underground railways and similar rail vehicles, labyrinth seals are often provided at the exit of the driven shaft extending out of the transmission housing in order to prevent penetration of spraying water and dirt into the interior of the transmission housing. These seals have proven to be successful. However, they are not sufficient when the vehicles must travel over flooded rail systems, which is often necessary during flood conditions. Transmission housings equipped with lip seals must be provided in such cases. Because of the wear of the seal lips caused by dust, dirt and influences of this nature, such seals have, as a rule, only a short service life, shorter than the time period between two inspections of the vehicles. A replacing of the seals within the time period between inspections is considered by the vehicle operators to be an imposition because of the enormous amount of work (the drive wheels and, if necessary, also the braking disks and the joint couplings must for this purpose be removed from the axle and must later on again be mounted) and the thus encountered expenses (longer down time of the vehicle). The arrangement of three lip seals acting one behind the other, as this is known from the Reference "FORSHEDA V-RING" of the Firm M. Merkel GmbH & Co. KG Hamburg (1982), Page 30, does not permit one to expect a significant service life extension.
Starting out from the abovesetforth deficiencies of known transmission seals, the basic purpose of the invention is to provide a transmission housing with a seal which functions satisfactorily and reliably over a long time period.